We got a dehumidifier with a water pump recently and I'm just now looking for a place to drain the water. What about using this p trap in the middle of this pic:
I believe that brown rubber hose is an overflow pump from another appliance (I'm forgetting what, off hand). Is there any reason I wouldn't want to set up a dehumidifier to pump about 2 gallons of water a day into that pipe?
Should be fine. All HVAC equipment that make condensate drain into risers just like this, no need for air gap because the source of the water is not connected to the potable water system in the house.
What is is - a trap, as you already noted. Should be fine, though I believe that technically both pipes (i.e. the current one and the one you are adding) should be fixed slightly ABOVE the pipe (air gap) rather than stuck into it (potential for siphoning.)
